“Mom. Can I do another 24?”

This request was music my math mom ears. It could be that the 9-year-old was only asking as a ruse to prolong bedtime. Frankly, if he was, then I will take that bait every time. Who can say no to a kid who wants to do more math??

24 is a card game. The cards look like this…

The goal is to make the number 24 using all 4 numbers on the face of one card. You must use each number, and you may use each number only once. So, for the top-left card above, one possible answer is 71 = 6, 2 + 2 = 4, and then 6 x 4 = 24. There are often multiple solutions on a single card, though I haven’t found another one for that particular card. If you find another way to use 7, 1, 2, and 2 to make 24, let me know!

I’ve had this set of cards for many years. Many years. A teacher colleague introduced me to them. Though the game is appropriate for kids as young as 9 (so says the box…really the main prerequisite is that you know your basic addition, subtraction, multiplication, and division facts within the 24 range), it can be challenging for anyone because the key to success is mental flexibility and persistence. I use this game frequently with my tutoring clients. I had not thought to use it with my own son until one night when he was just a little too rambunctious before bedtime and I wanted him to calm down.

“Hey,” I said, “Check this out.” And I tossed a card in his direction. I had tutored earlier in the day, and the cards were still out on the coffee table. As he picked it up, I pulled out one of our big whiteboards and a handful of colorful Expo markers. At the top of the whiteboard I wrote: 2 x 12 = 24, 3 x 8 = 24, and 4 x 6 = 24.

“Can you make the number 24 out of those 4 numbers on the card? You can add, subtract, multiply or divide to make it happen.”

His first inclination was to add them all together. But that didn’t work. So I let him marinate in his thoughts for a bit. Then I pointed out the equations that I had written and suggested that he look for ways to make numbers that could then multiply to 24. Then I left the room, claiming that I had to check on his brother. (Parents have ruses, too…this one was so that he didn’t have an audience for any drama that might unfold as he worked through this problem.) He came up with: 8 – 4 = 4, 3 + 3 = 6, and 4 x 6 = 24.

He enjoyed the game enough to try a few more cards before (happily!) heading to bed. Yay!

(Mathematically…at least 3 things are happening in this game that are great for you and your child. First, your child is getting practice not just with math facts, but also with being flexible with her math facts. She is working her numerical manipulation and mental flexibility muscles. Second, you are observing and learning about your child’s thought processes and learning style. Your observations can then become references in the conversations you have with your child’s teacher and inform the ways you interact effectively with your child. Third, working with the white board (or any recording medium) opens up the conversation for other mathematical topics and discussion. I introduced my son to notation with parentheses (remember order of operations and PEMDAS??) and we discussed whether or not an equation was allowed to have more than one equal sign. He said no; I said maybe. It’s an ongoing discussion.)